My pool ended up a nasty dark green over the winter again. I started a SLAM and the water has shown considerable improvement. It has become a very light green but seems to have gotten stuck and is not clearing further. I can just barely see the bottom of the pool. I'm still losing around .5 ppm of chlorine overnight. I have scooped out all the leaves I can get and I'm brushing the pool and backwashing the sand filter on a regular basis. I know I'm still getting stuff out of the pool because the water coming out when I backwash is dirty at first. I had lost all my CYA over the winter but managed to get it back up to 30 by using a few pouches of shock. Other than that I've been maintaining my shock level using bleach. I'm getting a little frustrated because it seems I have hit a wall in the SLAM process. The only thing I can think of that I've done wrong is that I forgot to get the PH level balanced before I started the SLAM. I don't think I can fool with it now because the high chlorine level will make the PH test inaccurate. Thoughts?
Started Slam but forgot about PH
- Thread starter Noah_Count
- Start date
borjis
LifeTime Supporter
Was the PH at a proper level (7.5-7.8)before you started?
If so it likely is not affecting it....at least for me it wasn't.
I did a SLAM for mustard algae last summer and completely forgot to lower ph, it was at 7.5 but
I was done and clear within a week regardless.
Are you sure you've kept the chlorine level high enough the entire time?
Running the pump 24/7 and uncovered?
If so it likely is not affecting it....at least for me it wasn't.
I did a SLAM for mustard algae last summer and completely forgot to lower ph, it was at 7.5 but
I was done and clear within a week regardless.
Are you sure you've kept the chlorine level high enough the entire time?
Running the pump 24/7 and uncovered?
- Jul 3, 2013
- 9,028
- Pool Size
- 15000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool SJ-40
You have found the worst part of the sand filter, it is great at filtering but it does take the longest of all the filters to clear your pool... backwashing all the time if not needed is really hurting you more than helping, sand filters work better dirty. still follow the 25% rise in pressure, if you are doing it then it is fine but don't do it just because..
You can add DE or cellulose-fiber ONLY if you can watch it closely, it can filter way faster but the pressure will also rise very fast.. Pool School - Add DE to a Sand Filter
You can add DE or cellulose-fiber ONLY if you can watch it closely, it can filter way faster but the pressure will also rise very fast.. Pool School - Add DE to a Sand Filter
If you are still getting gunk out, you have more work ahead of you. Have you checked behind any lights, ladders, weirs, etc?
I completely forgot to test PH at all when I started so I have no idea what it was. The gauge on my filter is not all that accurate so I've been backwashing when I notice a greatly reduced flow from the return. The pump is running 24/7. I test the water in the morning and then use the pool calculator to tell me how much bleach to add to bring it back up to shock level. I add the bleach and then wait a few hours for it to get mixed in good and then I test again to make sure I'm up to shock level. Usually I end up a little bit above. This isn't my first SLAM so I think I'm doing things as I should. I just forgot about fooling with the PH before I started.
This pool originally had a paper cartridge filter so their is still a place for it attached to the skimmer on the outside wall. I don't put a cartridge in there anymore because I have the sand filter now. I do have a brand new cartridge though. It was ordered before I decided to switch to the sand filter. I'm considering putting the cartridge in. It won't hurt anything and will provide some extra filtration.
This pool originally had a paper cartridge filter so their is still a place for it attached to the skimmer on the outside wall. I don't put a cartridge in there anymore because I have the sand filter now. I do have a brand new cartridge though. It was ordered before I decided to switch to the sand filter. I'm considering putting the cartridge in. It won't hurt anything and will provide some extra filtration.
The ladder was completely removed from the pool after swimming season. There is a light attached to the return but I have cleaned it and all around it. There was a lot of leaves in the pool but I have been diligently scooping them out every day until there are very few left that I can see. There was also a dead possum in the pool when I started, needless to say, I got rid of him!
- May 23, 2015
- 24,380
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
pH is going to have minimal effect on the sanitizing rate of the chlorine. The reason why TFP suggests lowering the pH initially is because large bleach additions, like the kind used during the start of a SLAM, can cause a temporary rise in pH. That rise in pH can sometimes cause clouding of the water if other parameters are off (like high TA and CH). So the lowering of the pool's pH is merely precautionary and should have no impact on the ability of the chlorine to kill algae.
It sounds to me like you have a filtration problem. Typically speaking, during a SLAM, most of the algae and biological contaminants are killed in the first few hours to days. Once your chlorine starts to hold (you're reporting only a 0.5ppm drop overnight), then that is a sign that most of the algae is dead and you are simply just oxidizing all of the organic contaminants in your pool. The "stall phase" is typically indicative of the slow filtration process caused by your sand filter as sand filters alone are not very good at clearing algae (dead or alive). At this point, you could consider a filtration aid like adding DE to the sand filter to help clear the water faster.
Let me ask you this - when was the last time you deep cleaned your sand filter? You could have deep channeling in the sand which means all of the "dirty water" is simply bypassing your sand and going straight back into the pool. Some people, when stuck in the "stall phase", have taken apart their filters and deep cleaned them to make sure they are operating at peak performance. Usually they find a pretty disgusting mess inside the filter when they tear it apart. It's up to you...
It sounds to me like you have a filtration problem. Typically speaking, during a SLAM, most of the algae and biological contaminants are killed in the first few hours to days. Once your chlorine starts to hold (you're reporting only a 0.5ppm drop overnight), then that is a sign that most of the algae is dead and you are simply just oxidizing all of the organic contaminants in your pool. The "stall phase" is typically indicative of the slow filtration process caused by your sand filter as sand filters alone are not very good at clearing algae (dead or alive). At this point, you could consider a filtration aid like adding DE to the sand filter to help clear the water faster.
Let me ask you this - when was the last time you deep cleaned your sand filter? You could have deep channeling in the sand which means all of the "dirty water" is simply bypassing your sand and going straight back into the pool. Some people, when stuck in the "stall phase", have taken apart their filters and deep cleaned them to make sure they are operating at peak performance. Usually they find a pretty disgusting mess inside the filter when they tear it apart. It's up to you...
I just installed the sand filter last year so I hadn't considered opening it up. I really don't want to but if this goes on much longer I guess I'll have to.
- May 23, 2015
- 24,380
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
TFP recommends tearing down and deep cleaning a sand filter at least once per year to ensure proper operation.
I would suggest you first use a filtration aid such as DE or cellulose fiber like CowboyCasey mentioned. A chemical clarifier might help, but we usually don't recommend them because there's no one simple process for using them and no way to know how much will work during a SLAM (high FC levels makes using other chemicals difficult to predict). I know people have used them in the past to help with clearing up residual cloudiness but the success rate is just too low for TFP to properly advise on their use. Try the DE first as it's the simplest approach, there's no interaction with FC and you can easily get rid of it just by backwashing.
I'll have to find a source for DE. There are no pool stores in my area. I have used clarifier before but that was after my water was already virtually clear. At that point the clarifier made the water crystal clear with a "polished" look to it. I was pleased with it then but I don't think my water is clear enough yet to even consider that.
One other thing that puzzles me. If I have in fact killed all the algae and the problem is filtration, wouldn't the water turn more to a cloudy white rather than remaining a light green color? It's been my understanding from reading here that the algae turns white when it dies and the white is what needs to be filtered out. The last SLAM I did, the water was light green like it is now and then it turned a bit cloudy before finally clearing. That was the first year that I used the sand filter though so I would imagine that it was running more efficiently.
Btw, I get my DE at Home Depot. Pool Time 25 lb. D.E. Filter Powder 23792PTM at The Home Depot - Mobile